Layshaft - groove too shallow for interlocking tab?

[gs.davies]

Has anyone run into this problem before?

I've been cursing at the interlocking tab behind the main bearing retainer for the past hour, trying to get it all to line up, along with the shim so I can get a screw into the gearbox casing. There is no way the interlocking tab wants to line up with the screw hole and eventually I decided to compare the groove on the new with the groove on the old.

Max depth on the old shaft 0.235"
Max depth on the new shaft 0.175"

Is this why I can't get the thing to line up? Or is there something else I'm overlooking?

Shaft is 4 synchro pre a plus type 2 step 22G931 from Somerford.

[imack]

I've got a used minispares competition 2 step shaft from a remote box, groove in that one is only 0.160".
Never had a problem fitting it although those locking plates can be fiddly to get the correct orientation of the reverse gear shaft and layshaft to get the plate located.

[Vegard]

Never had the problem, after rebuilding at least 50 gearboxes.

Easy fix though.

[gs.davies]

Well, I can get the screw hole close, but not close enough to allow the screw to pass through the hole and engage the thread in the gearbox casing. And that's after a good hour of sodding about trying to find the sweet spot where it all lines up.

Somerfords are having a look at their other stock but in the event that this is how it is, what's best to do? Remove a bit of material from the interlocking tab? I don't really see why something should require fettling to fit a part that is supposed to be machined to certain dimensions though. Or am I just being picky and awkward?

[imack]

Just measured two more used minispares layshafts.
One measures 0.203", the other is 0.165" so they're pretty inconsistent.
My used shafts have all been fitted in the same gearbox case using the same reverse gear shaft and same locking plate.
I guess if you've got a stack up of tolerances in unfavorable directions you may not get the locking plate to fit.

[gs.davies]

Post script.

Replacement lay shaft arrived today. It’s got 0.175 in the groove and the whole thing went together without drama...

Gearbox now complete and waiting for marrying up to engine. Things moving on.

[imack]

If both shafts had 0.175" grooves how come the first one didn't fit?

[gs.davies]

If both shafts had 0.175" grooves how come the first one didn't fit?

Typo in the original post. Original shaft had 0.160 in it